The invention concerns a method for representation of a subject represented in a volume data set.
Images acquired with modern imaging medicine-related apparatuses in particular exhibit a relatively high resolution, such that enhanced 3D exposures (volume data sets) can be generated with them. Imaging medicine-related apparatuses include, for example, ultrasound, computer tomography, magnetic resonance or x-ray apparatuses or Positron Emission Tomography (PET) scanners. Furthermore, computer tomography (CT) or x-ray apparatuses can be used more often since a radiation exposure that an organism is exposed to during an examination with one of these apparatuses has decreased.
However, volume data sets contain a larger data quantity than image data sets of conventional two-dimensional images, which is why an evaluation of volume data sets is relatively time-consuming. The actual acquisition of the volume data sets lasts approximately half a minute, in contrast to which a half-hour or more is often needed to thin out and prepare the volume data set. Automatic detection and preparation methods are therefore necessary and welcome.
Until approximately the year 2000, it was typical (nearly) only in computer tomography (CT) to make a diagnosis using axial slice stacks (slice images) or to at least orient oneself predominantly on the slice images for a diagnosis finding. Thanks to the increased computing capacity of computers, 3D representations have expanded to finding consoles since approximately 1995; however, they initially had a more scientific or supplementary importance. In order to make a diagnosis easier for a doctor, four basic methods of 3D visualization have also been developed:
1. Multiplanar reformatting (MPR): This is nothing other than a reconfiguration if the volume data set is in a different orientation than, for example, the original horizontal slices. In particular, differentiation is made between orthogonal MPR (3 MPRs, respectively perpendicular to one of the original coordinate axes), free MPR (angled slices; derived, i.e., interpolated) and curved MPR (slice generation parallel to an arbitrary path through the image of the body of the organism and, for example, perpendicular to the MPR in which the path was plotted).
2. Shaded surface display (SSD): Segmenting of the volume data set and representation of the surface of the excised objects, most strongly characterized by orientation to the gray values of the image (for example, CT values) and manual auxiliary editing.
3. Maximal intensity projection (MIP): Representation of the highest intensity along each ray. Only a partial volume is represented in what is known as Thin MIP.
4. Volume rendering (VR): This is a modeling using rays that penetrate into the subject or exit from the subject comparable to x-rays. The entire depth of the imaged body (partially translucent) is thereby acquired; however, details of small objects and especially objects shown in a thin layer are lost. The representation is manually characterized by adjustment of “transfer functions” (color lookup tables). Illumination effects can be to be mixed in, in that further storage planes are used in which gradient contribution and direction for the illumination are stored and allowed for in the representation.
However, a disadvantage of the known methods is the insufficient representation of relatively fine structures, particularly when a relatively large volume data set is present. A further disadvantage of the known method is that respectively only the entire 3D block is shown in a fixed context.